A xenohormone is a foreign, man-made hormone that has toxic effects on the human body. Xenohormones are most commonly found in plastics, pesticides, acetones (e.g. nail polish remover), and in industrial pollutants such as PCBs. Because they are a foreign substance and the body doesn't know how to get rid of them, xenohormones tend to accumulate in the body over time. Xenohormones can be particularly damaging to a developing fetus, and xenoestrogens in particular may increase a woman's risk of breast cancer.